Number of idempotent 3X3 -n..n matrices of rank 1.

Terms

a(0) =87a(1) =447a(2) =999a(3) =1935a(4) =2871a(5) =5079a(6) =6399a(7) =8679a(8) =10971a(9) =14667a(10) =16755a(11) =22323a(12) =24795a(13) =29979a(14) =35643a(15) =41019a(16) =44259a(17) =53139a(18) =56763a(19) =66123a(20) =74043a(21) =82203a(22) =86595a(23) =100035a(24) =106755a(25) =116403a(26) =125091a(27) =138243a(28) =143787a(29) =165627